The son of the smart set's favorite Beatle impressed an exclusive crowd at The Rose Bar on Friday night with his latest musical project, "The Ghost of a Saber-Toothed Tiger," which consists of himself on guitar and vocals, a drummer, keyboardist and his longtime girlfriend Charlotte Kemp Muhl on backup vocals.

The all-original set was "pretty heavy indie rock," says one reveler who caught the show, "and then for the last song he asked if he could play something softer."

Unfortunately, the crowd, hopped up on free drinks and cinematic bloodletting wasn't exactly in a mellow mood. "They were shouting, "'No! More metal! More rock!' " reports our spy, but the young Lennon stuck to his guns, closing his set with an acoustic duet with Muhl.

"Some people were still bummed it was the way he finished the show," our spy says, but others appreciated that "the song was reminiscent of his parents" - that would be John Lennon and Yoko Ono for anyone born recently or exceptionally clueless.

He wasn't the only famous offspring Rose Bar-goers were rubbing elbows with that night: Jake Hoffman, who stars in "Rosencrantz", was present to watch the performance.

"People were coming up to him and going, 'I'm such a fan of your dad's [Dustin Hoffman] . . . and you'" laughs an insider at the event. "He was really good-natured about the whole thing, and seemed to be having a great time."